Rubber article



Oct. 23, 1934. c; G HSHER 1,978,301

RUBBER ARTICLE Filed Feb. 11 1935 I Uarl 612m Patented Oct. 23, 1934 7 UNITED STATES PAT NT OFFICE RUBBER ARTICLE 7 Carl G. Fisher, Miami Beach,.Fla. Application February 11, 1933, Serial No. 656,348 2 claims. (o1'.j 1s 59)-,

This invention relates to improved rubber compositions and its object is to providea new composition which will have greater frictional characteristics and which will wear longer than such i compositions as heretofore known. I l l M I Pure rubber, although well adapted for countless uses nevertheless in its pure state is not suited for many uses where a high frictional characteristic is desired and Where it is subject to very r310 severe wear. I have found that by incorporation certain abrasive material in the body of the pure rubber that it will wear very much longer and will have a high frictional co-efficient which particularly well adapts it for such uses as auto- 151 mobile tires, shoe soles, and heels, belts, pulleys and many other uses.

Referring to the accompanying drawing which is made a part hereof and on which similar reference characters indicate similar parts,

ag Figures 1, 2 and 3 show sections of an automobile tire, a shoe heel and a belt, respectively. The figures of the drawing illustrate articles made of my new composition showing the side of the articles which is subject to the greatest wear as having a greater proportion of abrasive material incorporated therein and the side which is not subject to wear as having a lesser amount of abrasive material and more of the rubber material whereby this portion of the article has a higher degree of resiliency.

In preparing the composition the purpose for which it is to be used will determine somewhat the relative proportions of abrasive material and of rubber. The purpose for which used may also govern the kind of abrasive material which is used as a filler. Where the resiliency of the article is of the greater importance, a greater percentage of rubber in proportion to abrasive material will be used. Where the article is subject to severe wear, the abrasive characteristics or the wearing qualities of the article will be of the most importance and hence the articles will be made of a greater percentage of abrasive material, with only so much of rubber material as may be necessary to thoroughly bind the abrasive material together. As illustrated in the above drawing the wearing side 11 of the tire is made of a very large percentage of hard abrasive material, the particles of which are close together yet embedded in and isolated by the rubber which serves also as the binding material. The particles however will be so close together as to receive substantially the whole of the abrasive action with which the article contacts. When the material is used in the manufacture of automobile tires the tread of the tire will be largely constituted of abrasive material ,bound together with rubber. Moving from the outer tread of the tire towards the center the abrasive material will be decreased and the rubber increased in proportion so that the 80 side 12 will have a higher degree of resiliency and will not have so great an abrasive effect on the canvas or other lining 13.

The percentage of abrasive material may vary. Tests have shown that from 5 to percent of the whole body of the material may be abrasive. Some of the abrasive materials which have been found well adapted for my purpose are silica sand, emery dust, metal filings and ground glass. The use of ground glass has been found particularly advantageous because of its hardness.

Figure 2 illustrates the invention as applied to a shoe heel where the tread 14 has a high percentage of abrasive material and the back 15 a low percentage of abrasive material with the body portion of decreasing amount of abrasive from the tread to the rear.

In the belt shown in Figure 3 the side 16 which contacts with a driving or driven pulley contains a high percentage of abrasive material. This is the side which is subject to wear and which must drive the pulley by frictional engagement therewith. The rear side 17 of the belt must follow about a larger circumference of the pulley and should have enough resiliency to permit free travel about the pulley. This side is not subject to wear. My construction provides the ideal condition for a belt.

Some of the characteristics of my new product are a high co-efficient of friction, a relatively high heat conductivity and a great surface hardness. Due to the process of manufacture each of the particles of abrasive material is coated with the elastic material so that each abrasive particle is isolated from its neighbor. This provides a resilient binding connection between the particles and yet holds the particles in such a position as will cause them to receive the wear to which the article is subjected.

When incorporated in the rubber and the whole mass vulcanized the rubber supplies the holding medium or retaining medium for the glass or other abrasive material while the glass itself receives the wear. Due to the hardness of glass, it should be apparent that products made of a composition having an appreciable percentage of glass incorporated therein would have a very long life. As stated above the percentage of abrasive material may vary. I have found it possible and practical to vary the percentage of abrasive mate rial all the way from 5 to 25 percent of the volume of the whole mass. The abrasive material is thoroughly mixed in and thus incorporated with the body of the rubber and the mass vulcanized. In actual practice I have found that automobile tires made of my new rubber composition have been run ten thousand miles after which they showed less deterioration than tires made from any other material.

While specific abrasive materials have been specified and have given good results, I do not limit the invention to the use of these alone. Other abrasive materials may be found which may be used with equally good, or at least with satisfactory results.

It will be obvious to those skilled in the art that various changes may be made in my composition, without departing from the spirit of the invention and therefore I do not limit myself to what is described in the specification but only as indicated by the appended claims.

Having thus fully described my said invention, what I claim as new and desire to secure by Letters Patent, is:

1. An article of manufacture comprising a body portion'built up of sharp abrasive material in granular form bound together with elastic material, the outer or wear surface of the article having a high percentage of the abrasive material with a low percentage of elastic material, the rear of the article having a low percentage of abrasive material and a high percentage of elastic material, the percentage of elastic material gradually increased from the face to the back and the percentage of abrasive material gradually increased from the back to the front, substantially as set forth.

2. An article of manufacture comprising a body portion built up of a mixture of ground glass and silica sand bound together with rubber, the outer or wear surface of the article having a high percentage of sand and glass with a relatively low percentage of rubber, the back portion of the article having a small percentage of the mixture of sand and glass and a relatively high percentage of rubber, the percentage of rubber gradually increasing from the face to the back and the percentage of sand and glass gradually increasing from the back to the front whereby the face of the article has a hard surface with high friction co-efficient, whereas the back of the article is relatively elastic.

CARL G. FISHER. 

